1. Field of the Invention
The present invention relates to a process for producing .beta.-trifluoromethylpyridines directly from .beta.-picoline or a chloro .beta.-picoline, in particular, a process for producing .beta.-trifluoromethylpyridines (hereinafter referring to as .beta.-TFP.sub.s) by a vapor phase reaction of .beta.-picoline or a chloro .beta.-picoline with chlorine and anhydrous hydrogen fluoride in the presence of a special catalyst.
2. Description of the Prior Art
.beta.-TFP.sub.s are compounds useful as intermediates for dyes, medicines or agricultural chemicals such as herbicides and insecticides. The industrial values of these compounds are significant recently.
As the process for producing the .beta.-TFP.sub.s, it has been known that chlorine gas is fed into a solution of .beta.-picoline in carbon tetrachloride under an irradiation of ultraviolet rays to produce .beta.-trichloromethylpyridines, and the .beta.-trichloromethylpyridines are reacted with anhydrous hydrogen fluoride or antimony trifluoride by a liquid phase reaction. However, this process requires a long time for the reaction and produces a large quantity of by-products to be a low yield. Therefore, it is not satisfactory as an industrial process.
The present inventors discovered a process for producing .beta.-TFP.sub.s by a vapor phase reaction of .beta.-picoline or chloro .beta.-picolines with chlorine and anhydrous hydrogen fluoride in the presence of a certain fluoride of metallic element and diluent. They also gained the discovery that this process was able to provide the object product in a single step and for short time to resolve the defects of said conventional process, and proposed patent application of British Patent Publication 2045245.